Damalinia bovis lice and a hernia

Going over her today I noticed she is infested with lice; Damalinia bovis. I have Co-Ral dust for the goats, says it treats biting and sucking lice. How many treatments should it take to kill them and the eggs? Should I bathe her first?
Also what can anyone tell me about horse hernias?
Two pics attatched.

Treating for lice requires that you treat 3 times, 10 days apart. Bathing your horse before applying powder will not improve it's effectiveness. (Just FYI, horses get Daminilinia equi they look very very much like Daminilia bovis.)

Hernia's should be examined by your vet to ensure that they are not large enough to allow loops of intestine to pass through the muscle wall and get trapped.

Ok, so those lice are just about the most disgusting thing I've seen in a while....